NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This study was supported by Contract No. SP8000-06-C-0013 between the National Academy of Sciences and the U.S. Department of Defense. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the organizations or agencies that provided support for the project.

Cover: A titanium splash. Titanium is a light, strong, lustrous, corrosion-resistant metal that can withstand extreme temperatures. Titanium alloys have many uses in military systems, including in aircraft, armor plating, naval ships, spacecraft, and missiles. SOURCE: Gerald Petrak, Wright-Patterson Air Force Base.